Abstract: The measuring principle and experiment of Laser Ultrasonic Pulse by Laser Heterodyne Interfermetric Method is described. The effect of collimation angle of signal light、reference light upon S/N radio is discussed, and the effect of incidence of signal light upon bean spliter on heterodyne signal intensity is discussed too. In order to increase the detective signal intensity, the method of heterodyne interferomtric conjugate output is developed.